Organic light emitting display device

ABSTRACT

An organic light emitting display device driven at a first driving frequency or a second driving frequency lower than the first driving frequency includes pixels coupled to first scan lines, second scan lines, and data lines, a first scan driver configured to supply scan signals to the first scan lines during a first period and a second period in one frame period, when the organic light emitting display device is driven at the second driving frequency, a second scan driver configured to supply scan signals to the second scan lines during the first period, when the organic light emitting display device is driven at the second driving frequency, and a data driver configured to supply a data signal to the data lines during the first period.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2017-0046813, filed on Apr. 11, 2017, in the KoreanIntellectual Property Office, the entire disclosure of which isincorporated by reference herein.

BACKGROUND 1. Field

An aspect of the present disclosure relates to an organic light emittingdisplay device, and more particularly, to an organic light emittingdisplay device capable of improving display quality.

2. Description of the Related Art

With the development of information technologies, the importance of adisplay device, which is a connection medium between a user andinformation, increases. Accordingly, display devices such as a liquidcrystal display device and an organic light emitting display device areincreasingly used.

Among these display devices, the organic light emitting display devicedisplays images using organic light emitting diodes that generate lightby recombination of electrons and holes. The organic light emittingdisplay device has a high response speed and has low power consumption.

Recently, a method for driving an organic light emitting display deviceat a low frequency has been used so as to reduce or minimize powerconsumption. What is desired is a method capable of improving displayquality when an organic light emitting display device is driven at a lowfrequency.

SUMMARY

Aspects of embodiments of the present disclosure are directed to anorganic light emitting display device capable of improving displayquality.

According to an embodiment of the present disclosure, there is providedan organic light emitting display device configured to be driven at afirst driving frequency or a second driving frequency that is lower thanthe first driving frequency, the organic light emitting display deviceincluding: pixels coupled to first scan lines, second scan lines, anddata lines; a first scan driver configured to supply scan signals to thefirst scan lines during a first period and a second period in one frameperiod, when the organic light emitting display device is driven at thesecond driving frequency; a second scan driver configured to supply scansignals to the second scan lines during the first period, when theorganic light emitting display device is driven at the second drivingfrequency; and a data driver configured to supply a data signal to thedata lines during the first period.

In an embodiment, when the organic light emitting display device isdriven at the first driving frequency, the first scan driver isconfigured to supply scan signals to the first scan lines during the oneframe period, and the second scan driver is configured to supply scansignals to the second scan lines during the one frame period.

In an embodiment, when the organic light emitting display device isdriven at the first driving frequency, a scan signal supplied to an ith(i being a natural number) first scan line overlaps with that suppliedto an ith second scan line.

In an embodiment, the data driver is configured to supply the datasignal to be synchronized with the scan signals supplied to the firstscan lines.

In an embodiment, when the organic light emitting display device isdriven at the second driving frequency, the first scan driver isconfigured to supply j (j being a natural number of 2 or more) scansignals to each of the first scan lines during the one frame period, andthe second scan driver is configured to supply k (k being a naturalnumber smaller than j) scan signals to each of the second scan linesduring the one frame period.

In an embodiment, during the first period, a scan signal supplied to anith (i being a natural number) first scan line overlaps with thatsupplied to an ith second scan line.

In an embodiment, the second period is longer than the first period.

In an embodiment, the first scan driver is configured to supply a scansignal to each of the first scan lines at least twice or more during thesecond period.

In an embodiment, the data driver is configured to supply a voltage of areference power source to the data lines during the second period.

In an embodiment, the reference power source is set to a voltage withina voltage range of data signals supplied from the data driver.

In an embodiment, the organic light emitting display device furtherincludes: emission control lines in parallel to the first scan lines,the emission control lines being coupled to the pixels; and an emissiondriver configured to supply emission control signals to the emissioncontrol lines during a period in which the organic light emittingdisplay device is driven at the first driving frequency, the firstperiod, and the second period.

In an embodiment, an emission control signal supplied to an ith (i beinga natural number) emission control line overlaps with a scan signalsupplied to an ith first scan line during at least a partial period.

In an embodiment, each of pixels at an ith (i being a natural number)horizontal line includes: an organic light emitting diode; and a pixelcircuit configured to control an amount of current flowing from a firstdriving power source to a second driving power source via the organiclight emitting diode.

In an embodiment, the reference power source is set to a voltagedifferent from that of the first driving power source.

In an embodiment, the pixel circuit includes: a first transistor coupledto the first driving power source via a first node coupled to a firstelectrode thereof, the first transistor being configured to control theamount of current supplied to the organic light emitting diode, theamount of current corresponding to a voltage of a second node; a secondtransistor coupled between a data line and the first node, the secondtransistor being configured to turn on when a scan signal is supplied toan ith first scan line; a third transistor coupled between a secondelectrode of the first transistor and the second node, the thirdtransistor being configured to turn on when a scan signal is supplied toan ith second scan line; a fourth transistor coupled between the secondnode and an initialization power source, the fourth transistor beingconfigured to turn on when a scan signal is supplied to an (i−1)thsecond scan line; and a fifth transistor coupled between the first nodeand the first driving power source, the fifth transistor beingconfigured to turn off when an emission control signal is supplied to anith emission control line.

In an embodiment, the first transistor, the second transistor, and thefifth transistor are P-type transistors, and the third transistor andthe fourth transistor are N-type oxide semiconductor transistors.

In an embodiment, the pixel circuit further includes: a sixth transistorcoupled between the second electrode of the first transistor and ananode electrode of the organic light emitting diode, the sixthtransistor being configured to turn off when the emission control signalis supplied to the ith emission control line; and a seventh transistorcoupled between the anode electrode of the organic light emitting diodeand the initialization power source.

In an embodiment, the seventh transistor is a P-type transistor, and isconfigured to turn on when the scan signal is supplied to the ith firstscan line.

In an embodiment, the seventh transistor is an N-type transistor, and isconfigured to turn on when the emission control signal is supplied tothe ith emission control line.

In an embodiment, the seventh transistor is an N-type transistor, and anith third scan line is coupled to a gate electrode of the seventhtransistor, and a scan signal supplied to the ith third scan lineoverlaps with the emission control signal supplied to the ith emissioncontrol line.

In an embodiment, the pixel circuit includes: an eleventh transistorconfigured to control the amount of current supplied from the firstdriving power source coupled to a first electrode thereof to the organiclight emitting diode, the amount of current corresponding to a voltageof an eleventh node; a twelfth transistor coupled between a twelfth nodeand a data line, the twelfth transistor being configured to turn on whena scan signal is supplied to an ith scan line; a thirteenth transistorcoupled between the twelfth node and an anode electrode of the organiclight emitting diode, the thirteenth transistor being configured to turnoff when an emission control signal is supplied to an (i−1)th emissioncontrol line; a fourteenth transistor coupled between the eleventh nodeand the first electrode of the eleventh transistor, the fourteenthtransistor being configured to turn on when a scan signal is supplied toan ith second scan line; a fifteenth transistor coupled between aninitialization power source and the anode electrode of the organic lightemitting diode, the fifteenth transistor being configured to turn onwhen the scan signal is supplied to an ith first scan line; a sixteenthtransistor coupled between the first driving power source and the firstelectrode of the eleventh transistor, the sixteenth transistor beingconfigured to turn off when an emission control signal is supplied to anith emission control line; and a storage capacitor coupled between theeleventh node and the twelfth node.

In an embodiment, the eleventh to sixteenth transistors are N-typetransistors.

In an embodiment, the organic light emitting display device furtherincludes: third scan lines in parallel to the first scan lines, thethird scan lines being coupled to the pixels; and a third scan driverconfigured to supply scan signals to the third scan lines during thesecond period when the organic light emitting display device is drivenat the second driving frequency.

In an embodiment, the third scan driver is configured to supply no scansignal to the third scan lines during the period in which the organiclight emitting display device is driven at the first driving frequencyand in the first period.

In an embodiment, each of pixels at an ith (i being a natural number)horizontal line includes: an organic light emitting diode; a firsttransistor coupled to a first driving power source via a first nodecoupled to a first electrode thereof, the first transistor beingconfigured to control an amount of current supplied to the organic lightemitting diode, the amount of current corresponding to a voltage of asecond node; a second transistor coupled between a data line and thefirst node, the second transistor being configured to turn on when ascan signal is supplied to an ith first scan line; a third transistorcoupled between a second electrode of the first transistor and thesecond node, the third transistor being configured to turn on when ascan signal is supplied to an ith second scan line; a fourth transistorcoupled between the second node and an initialization power source, thefourth transistor being configured to turn on when a scan signal issupplied to an (i−1)th second scan line; a fifth transistor coupledbetween the first node and the first driving power source, the fifthtransistor being configured to turn off when an emission control signalis supplied to an ith emission control line; and an eighth transistorcoupled between the first node and a reference power source, the eighthtransistor being configured to turn on when a scan signal is supplied toan ith third scan line.

In an embodiment, the reference power source is set to a voltagedifferent from that of the first driving power source.

In an embodiment, an organic light emitting display device including: apixel including: a first transistor configured to control an amount ofcurrent flowing from a first driving power source to a second drivingpower source via an organic light emitting diode; a second transistorcoupled between a data line and a first electrode of the firsttransistor, the second transistor being configured to turn on when ascan signal is supplied to an ith (i being a natural number) first scanline; and a third transistor coupled between a second electrode and agate electrode of the first transistor, the third transistor beingconfigured to turn on when a scan signal is supplied to an ith secondscan line; a first scan driver configured to supply a scan signal to anith first scan line during a first period and a second period of oneframe period; a second scan driver configured to supply a scan signal tothe ith second scan line during the first period; and a data driverconfigured to supply a data signal to the data line during the firstperiod and to supply a voltage of a reference power source during thesecond period.

In an embodiment, the third transistor is set as an N-type oxidesemiconductor transistor.

In an embodiment, the second period is longer than the first period.

In an embodiment, the pixel further includes: a fourth transistorcoupled between the gate electrode of the first transistor and aninitialization power source, the fourth transistor being configured toturn on when a scan signal is supplied to an (i−1)th second scan line;and a fifth transistor coupled between the first electrode of the firsttransistor and the first driving power source, the fifth transistorbeing configured to turn off when an emission control signal is suppliedto an ith emission control line.

In an embodiment, the organic light emitting display device furtherincludes an emission driver configured to supply the emission controlsignal to the ith emission control line during the first period and thesecond period.

According to an embodiment of the present disclosure, there is providedan organic light emitting display device driven at a first drivingfrequency or a second driving frequency lower than the first drivingfrequency, the organic light emitting display device including: pixelscoupled to first scan lines, second scan lines, and data lines; a firstscan driver configured to supply scan signals to the first scan lines; asecond scan driver configured to supply scan signals to the second scanlines; and a timing controller configured to supply a same number ofgate start pulses to the first scan driver and the second scan driverwhen the organic light emitting display device is driven at the firstdriving frequency, and to supply different numbers of gate start pulsesto the first scan driver and the second scan driver when the organiclight emitting display device is driven at the second driving frequency.

In an embodiment, when the organic light emitting display device isdriven at the second driving frequency, the timing controller isconfigured to: supply l (l being a natural number of 2 or more) gatestart pulses to the first scan driver during one frame period; andsupply p (p being a natural number smaller than l) gate start pulses tothe second scan driver during the one frame period.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, the present disclosuremay be embodied in different forms and should not be construed aslimited to the embodiments set forth herein. Rather, these embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the example embodiments to those skilledin the art.

In the drawings, dimensions may be exaggerated for clarity ofillustration. Like reference numerals refer to like elements throughout.

FIG. 1 is a diagram schematically illustrating an organic light emittingdisplay device according to an embodiment of the present disclosure.

FIG. 2 is a circuit diagram illustrating an embodiment of a pixel shownin FIG. 1.

FIG. 3 is a waveform diagram illustrating an embodiment of a drivingmethod of the pixel shown in FIG. 2.

FIG. 4 is a waveform diagram illustrating another embodiment of thedriving method of the pixel shown in FIG. 2.

FIG. 5 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 2 is driven at a first drivingfrequency.

FIG. 6 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 2 is driven at a second drivingfrequency.

FIG. 7 is a diagram illustrating changes in characteristics of a drivingtransistor included in the pixel.

FIG. 8 is a waveform diagram illustrating gate start pulses supplied toa first scan driver and a second scan driver.

FIG. 9 is a circuit diagram illustrating another embodiment of the pixelshown in FIG. 1.

FIG. 10 is a waveform diagram illustrating an embodiment of a drivingmethod of the pixel shown in FIG. 9.

FIG. 11 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 9 is driven at the first drivingfrequency.

FIG. 12 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 9 is driven at the second drivingfrequency.

FIG. 13 is a circuit diagram illustrating still another embodiment ofthe pixel shown in FIG. 1.

FIG. 14 is a circuit diagram illustrating still another embodiment ofthe pixel shown in FIG. 1.

FIG. 15 is a circuit diagram illustrating still another embodiment ofthe pixel shown in FIG. 1.

FIGS. 16A-16B are waveform diagrams illustrating an embodiment of adriving method of the pixel shown in FIG. 15.

FIG. 17 is a circuit diagram illustrating still another embodiment ofthe pixel shown in FIG. 1.

FIG. 18 is a waveform diagram illustrating an embodiment of a drivingmethod of the pixel shown in FIG. 17.

FIG. 19 is a circuit diagram illustrating still another embodiment ofthe pixel shown in FIG. 1.

FIG. 20 is a waveform diagram illustrating an embodiment of a drivingmethod of the pixel shown in FIG. 19.

FIG. 21 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 19 is driven at the first drivingfrequency.

FIG. 22 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 19 is driven at the second drivingfrequency.

FIG. 23 is a diagram schematically illustrating an organic lightemitting display device according to another embodiment of the presentdisclosure.

FIG. 24 is a circuit diagram illustrating an embodiment of a pixel shownin FIG. 23.

FIG. 25 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 24 is driven at the first drivingfrequency.

FIG. 26 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 24 is driven at the second drivingfrequency.

FIG. 27 is a waveform diagram illustrating gate start pulses supplied toa first scan driver, a second scan driver, and a third scan driver,shown in FIG. 23.

DETAILED DESCRIPTION

In the following detailed description, only certain exemplaryembodiments of the present disclosure have been shown and described,simply by way of illustration. As those skilled in the art wouldrealize, the described embodiments may be modified in various differentways, all without departing from the spirit or scope of the presentdisclosure. Accordingly, the drawings and description are to be regardedas illustrative in nature and not restrictive.

FIG. 1 is a diagram schematically illustrating an organic light emittingdisplay device according to an embodiment of the present disclosure.

Referring to FIG. 1, the organic light emitting display device accordingto the embodiment of the present disclosure includes a pixel unit 100, afirst scan driver 110, a second scan driver 120, a data driver 130, atiming controller 140, a host system 150, and an emission driver 160.

The host system 150 supplies image data RGB to the timing controller 140through a set or predetermined interface. Also, the host system 150 maysupply timing signals Vsync, Hsync, DE, and CLK to the timing controller140.

The timing controller 140 generates a data driving control signal DCSand an emission driving control signal ECS, based on the image data RGBand the timing signals, such as a vertical synchronization signal Vsync,a horizontal synchronization signal Hsync, a data enable signal DE, anda clock signal CLK, which are supplied from the host system 150. Thedata driving control signal DCS generated by the timing controller 140is supplied to the data driver 130, and the emission driving controlsignal ECS generated by the timing controller 140 is supplied to theemission driver 160. Also, the timing controller 140 supplies a gatestart pulse GSP1 or GSP2 and clock signals CLK to the first scan driver110 and the second scan driver 120, based on the timing signals. Inaddition, the timing controller 140 realigns data RGB supplied from theoutside and supplies the realigned data RGB to the data driver 130.

The data driving control signal DCS includes a source start pulse andclock signals. The source start pulse controls a sampling start time ofdata. The clock signals are used to control a sampling operation.

The emission driving control signal ECS includes an emission start pulseand clock signals. The emission start pulse controls a first timing ofan emission control signal. The clock signals are used to shift (e.g.,shift in time) the emission start pulse.

A first gate start pulse GSP1 controls a first timing of a scan signalsupplied from the first scan driver 110. Clock signals CLK are used toshift (e.g., shift in time) the first gate start pulse GSP1.

A second gate start pulse GSP2 controls a first timing of a scan signalsupplied from the second scan driver 120. Clock signals CLK are used toshift (e.g., shift in time) the second gate start pulse GSP2.

The data driver 130 supplies a data signal to data lines D,corresponding to the data driving control signal DCS. The data signalsupplied to the data lines D is supplied to pixels PXL selected by ascan signal.

When the organic light emitting display device is driven at a firstdriving frequency, the data driver 130 supplies a data signal to thedata lines D during one frame period. In this case, the data signalsupplied to the data lines D may be supplied to be synchronized with(e.g., be at the same time as or overlapping) scan signals supplied tofirst scan lines S1 and second scan lines S2.

When the organic light emitting display device is driven at a seconddriving frequency lower than the first driving frequency, the datadriver 130 supplies a data signal to the data lines during a firstperiod in one frame period, and supplies a voltage of a reference powersource to the data lines D during a second period, and not the firstperiod. Here, the voltage of the reference power source may be set to aspecific voltage within a voltage range of a data signal. Additionally,the first period refers to a period in which scan signals are suppliedto the first scan lines S1 and the second scan lines S2. In addition,the second period refers to a period in which scan signals are suppliedto the first scan lines S1, and not the second scan lines S2.

The first scan driver 110 supplies scan signals to the first scan linesS1, corresponding to the first gate start pulse GSP1. In an embodiment,the first scan driver 110 may sequentially supply the scan signals tothe first scan lines S1. Here, the scan signals supplied from the firstscan driver 110 are set to a gate-on voltage such that transistorsincluded in the pixels PXL can be turned on.

The second scan driver 120 supplies scan signals to the second scanlines S2, corresponding to the second gate start pulse GSP2. In anembodiment, the second scan driver 120 may sequentially supply the scansignals to the second scan lines S2. Here, the scan signals suppliedfrom the second scan driver 120 are set to the gate-on voltage such thatthe transistors included in pixels PXL can be turned on.

The first scan driver 110 and the second scan driver 120 may controlscan signals supplied to the scan lines S1 and S2, corresponding to adriving frequency. In an embodiment, when the organic light emittingdisplay device is driven at the first driving frequency, the first scandriver 110 may sequentially supply one or more scan signals to each ofthe first scan lines S1 during one frame period. Similarly, when theorganic light emitting display device is driven at the first drivingfrequency, the second scan driver 120 may sequentially supply one ormore scan signals to each of the second scan lines S2 during one frameperiod. Here, a scan signal supplied to an ith (i is a natural number)first scan line S1 i overlaps with that supplied to an ith second scanline S2 i. In other words, the scan signal supplied to the ith firstscan line S1 i is supplied at the same time as the scan signal suppliedto the ith second scan line S2 i (i.e., the scan signals are supplied tobe synchronized with each other).

When the organic light emitting display device is driven at the seconddriving frequency, the first scan driver 110 supplies scan signals tothe first scan lines S1 during the first period and the second period.In an embodiment, the first scan driver 110 may supply j (j is a naturalnumber of 2 or more) to each of the first lines S1 during the firstperiod and the second period. Here, the scan signals supplied to each ofthe first scan lines S1 may be repeatedly supplied for every set orpredetermined period.

When the organic light emitting display device is driven at the seconddriving frequency, the second scan driver 120 supplies scan signals tothe second scan lines S2 during the first period. In an embodiment, thesecond scan driver 120 supplies k (k is a natural number smaller than j)scan signals to each of the second scan lines S2 during the firstperiod. Here, the scan signal supplied to the ith first scan line S1 ioverlaps with that supplied to the ith second scan line S2 i.

The emission driver 160 supplies emission control signals to emissioncontrol lines E, corresponding to the emission driving control signalECS. In an embodiment, the emission driver 160 may sequentially supplythe emission control signals to the emission control lines E. When theemission control signals are sequentially supplied to the emissioncontrol lines E, the pixels PXL emit no light in units of horizontallines. To this end, the emission control signals are set to a gate-offvoltage such that the transistors included in the pixels PXL can beturned off. Additionally, the emission driver 160 supplies an emissioncontrol signal to an ith emission control line Ei to overlap with scansignals supplied to an (i−1)th first scan line S1 i-1 and the ith firstscan line S1 i.

The pixel unit 100 includes pixels PXL that are coupled to the datalines D, the scan lines S1 and S2, and the emission control lines E. Thepixels PXL receive a first driving power source ELVDD, a second drivingpower source ELVSS, and an initialization power source Vint, which aresupplied from the outside (e.g., external to the pixel unit 100).

Each of the pixels PXL is selected when scan signals are supplied toscan lines S1 and S2 coupled thereto to receive a data signal suppliedfrom a data line D. The pixel PXL receiving the data signal controls theamount of current flowing from the first driving power source ELVDD tothe second driving power source ELVSS via an organic light emittingdiode, corresponding to the data signal. At this time, the organic lightemitting diode generates light with a luminance (e.g., a predeterminedluminance) corresponding to the amount of the current. In addition, theemission time of each of the pixels PXL is controlled by an emissioncontrol signal supplied from an emission control line E coupled to thepixel PXL.

Additionally, each of the pixels PXL may be coupled to one or more firstscan lines S1, one or more second scan lines S2, and one or moreemission control lines E, corresponding to circuit structures thereof.That is, in the embodiment of the present disclosure, signal lines S1,S2, E, and D coupled to the pixel PXL may be variously set correspondingto circuit structures of the pixel PXL.

FIG. 2 is a circuit diagram illustrating an embodiment of the pixelshown in FIG. 1. For convenience of description, a pixel that is locatedon an ith horizontal line and is coupled to an mth data line Dm isillustrated in FIG. 2.

Referring to FIG. 2, the pixel PXL according to the embodiment of thepresent disclosure includes an organic light emitting diode OLED and apixel circuit 200 for controlling the amount of current supplied to theorganic light emitting diode OLED.

An anode electrode of the organic light emitting diode OLED is coupledto the pixel circuit 200, and a cathode electrode of the organic lightemitting diode OLED is coupled to the second driving power source ELVSS.The organic light emitting diode OLED generates light with a luminance(e.g., a predetermined luminance) corresponding to the amount of currentsupplied from the pixel circuit 200.

The pixel circuit 200 controls the amount of current flowing from thefirst driving power source ELVDD to the second driving power sourceELVSS via the organic light emitting diode OLED, corresponding to a datasignal. To this end, the pixel circuit 200 includes first to fifthtransistors M1 to M5 and a storage capacitor Cst.

A first electrode of the first transistor (or driving transistor) M1 iscoupled to a first node N1, and a second electrode of the firsttransistor M1 is coupled to the anode electrode of the organic lightemitting diode OLED. In addition, a gate electrode of the firsttransistor M1 is coupled to a second node N2. The first transistor M1controls the amount of the current flowing from the first driving powersource ELVDD to the second driving power source ELVSS via the organiclight emitting diode OLED, corresponding to a voltage of the second nodeN2. To this end, the first driving power source ELVDD is set to avoltage higher than that of the second driving power source ELVSS.

The second transistor M2 is coupled between a data line Dm and the firstnode N1. In addition, a gate electrode of the second transistor M2 iscoupled to an ith first scan line S1 i. The second transistor M2 isturned on when a scan signal is supplied to the ith first scan line S1 ito allow the data line Dm and the first node N1 to be electricallycoupled to each other.

The third transistor M3 is coupled between the second electrode of thefirst transistor M1 and the second node N2. In addition, a gateelectrode of the third transistor M3 is coupled to an ith second scanline S2 i. The third transistor M3 is turned on when a scan signal issupplied to the ith second scan line S2 i to allow the second electrodeof the first transistor M1 and the second node N2 to be electricallycoupled to each other. Therefore, when the third transistor M3 is turnedon, the first transistor M1 is diode-coupled.

The fourth transistor M4 is coupled between the second node N2 and theinitialization power source Vint. In addition, a gate electrode of thefourth transistor M4 is coupled to an (i−1)th second scan line S2 i-1.The fourth transistor M4 is turned on when a scan signal is supplied tothe (i−1)th second scan line S2 i-1 to supply a voltage of theinitialization power source Vint to the second node N2. Here, thevoltage of the initialization power source Vint is set to a voltagelower than that of the data signal supplied to the data line Dm.

The fifth transistor M5 is coupled between the first driving powersource ELVDD and the first node N1. In addition, a gate electrode of thefifth transistor M5 is coupled to an emission control line Ei. The fifthtransistor M5 is turned off when an emission control signal is suppliedto the emission control line Ei, and is turned on otherwise.

The storage capacitor Cst is coupled between the first driving powersource ELVDD and the second node N2. The storage capacitor Cst stores avoltage applied to the second node N2.

The first to fifth transistors M1 to M5 are formed as P-typetransistors. In an embodiment, the first to fifth transistors M1 to M5may be formed as P-type poly-silicon semiconductor transistors.

FIG. 3 is a waveform diagram illustrating an embodiment of a drivingmethod of the pixel shown in FIG. 2.

Referring to FIG. 3, an emission control signal is first supplied to theemission control line Ei. When the emission control signal is suppliedto the emission control line Ei, the fifth transistor M5 is turned off.When the fifth transistor M5 is turned off, the electrical couplingbetween the first node N1 and the first driving power source ELVDD isinterrupted, and accordingly, the pixel PXL is set to a non-emissionstate.

After that, a scan signal is supplied to the (i−1)th second scan line S2i-1. When the scan signal is supplied to the (i−1)th second scan line S2i-1, the fourth transistor M4 is turned on. When the fourth transistorM4 is turned on, the voltage of the initialization power source Vint issupplied to the second node N2.

After the voltage of the initialization power source Vint is supplied tothe second node N2, a scan signal is supplied to each of the ith firstscan line S1 i and the ith second scan line S2 i. When the scan signalis supplied to the ith second scan line S2 i, the third transistor M3 isturned on. When the third transistor M3 is turned on, the firsttransistor M1 is diode-coupled.

If the scan signal is supplied to the ith first scan line S1 i, thesecond transistor M2 is turned on. When the second transistor M2 isturned on, a data signal Ds from the data line Dm is supplied to thefirst node N1. At this time, because the second node N2 is initializedto the voltage of the initialization power source Vint, which is lowerthan the voltage of the data signal DS, the first transistor M1 isturned on.

If the first transistor M1 is turned on, the data signal DS supplied tothe first node N1 is supplied to the second node N2 via thediode-coupled first transistor M1. Then, a voltage, corresponding to thedata signal DA and a threshold voltage of the first transistor M1, isapplied to the second node N2. At this time, the storage capacitor Cststores the voltage of the second node N2.

The supply of the emission control signal to the emission control lineEi is stopped after the voltage corresponding to the data signal DS andthe threshold voltage of the first transistor M1 is stored in thestorage capacitor Cst. When the supply of the emission control signal tothe emission control line Ei is stopped, the fifth transistor M5 isturned on. When the fifth transistor M5 is turned on, the first drivingpower source ELVDD and the first node N1 are electrically coupled toeach other. At this time, the first transistor M1 controls the amount ofcurrent flowing from the first driving power source ELVDD to the seconddriving power source ELVSS via the organic light emitting diode OLED,corresponding to the voltage of the second node N2. Then, the organiclight emitting diode OLED generates light with a luminance correspondingto the amount of the current.

Actually, the pixel PXL of the present disclosure is driven whilerepeating the above-described process. Additionally, for convenience ofdescription, a case where one scan signal is supplied to each of thescan lines S1 and S2 is illustrated in FIG. 3, but the presentdisclosure is not limited thereto. In an embodiment, a plurality of scansignals may be supplied each of the scan lines S1 and S2 as shown inFIG. 4. In this case, an operation process is substantially identical tothat of FIG. 3, and therefore, its detailed description may not berepeated. In the following description, it will be assumed that one scansignal is supplied to each of the scan lines S1 and S2.

FIG. 5 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 2 is driven at the first drivingfrequency. Here, the first driving frequency may be set to a frequencyof 60 Hz or more.

Referring to FIG. 5, when the organic light emitting display device isdriven at the first frequency, scan signals are sequentially supplied tofirst scan lines S11 to S1 n and second scan lines S21 to S2 n duringone frame period 1F. Here, a scan signal supplied to the ith first scanline S1 i overlaps with that supplied to the ith second scan line S2 i.

In addition, when the organic light emitting display device is driven atthe first frequency, emission control signals are sequentially suppliedto emission control lines E1 to En during the one frame period 1F. Here,an emission control signal supplied to the ith emission control line Eioverlaps with scan signals supplied to the (i−1)th first scan line S1i-1 and the ith first scan line S1 i. A data signal DS is supplied tothe data lines Dm to be synchronized with the scan signals.

Then, a voltage corresponding to the data signal DS is stored in each ofthe pixels PXL as described in FIGS. 2 and 3. In addition, each of thepixels PXL generates light with a luminance (e.g., a predeterminedluminance) corresponding to the data signal DS, so that the pixel unit100 can display an image (e.g., a predetermined image).

FIG. 6 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 2 is driven at the second drivingfrequency. Here, the second driving frequency may be set to a frequencyof less than 60 Hz.

Referring to FIG. 6, when the organic light emitting display device isdriven at the second driving frequency, one frame period 1F is dividedinto a first period T1 and a second period T2. Here, the second periodT2 may be set as a period wider (e.g., having a longer duration) thanthe first period T1.

During the first period T1, scan signals are sequentially supplied tothe first scan lines S11 to S1 n and the second scan lines S21 to S2 n.Here, a scan signal supplied to the ith first scan line S1 i overlapswith that supplied to the ith second scan line S2 i.

In addition, during the first period T1, emission control signals aresequentially supplied to the emission control lines E1 to En. Here, anemission control signal supplied to the ith emission control line Eioverlaps with scan signals supplied to the (i−1)th first scan line S1i-1 and the ith first scan line S1 i. A data signal DS is supplied tothe data lines D to be synchronized with the scan signals. Then, duringthe first period T1, a voltage corresponding to the data signal DS isstored in each of the pixels PXL.

During the second period T2, a plurality of scan signals are supplied toeach of the first scan lines S11 to S1 n. Here, the scan signalssupplied to each of the first scan lines S11 to S1 n may be supplied forevery set or predetermined period. In an embodiment, during the secondperiod T2, scan signals may be supplied several times to the first scanlines S11 to S1 n while being sequentially repeated.

During the second period T2, a plurality of emission control signals aresupplied to the emission control lines E1 to En. Here, an emissioncontrol signal supplied to the ith emission control line Ei may besupplied to overlap with scan signals supplied to the (i−1)th first scanline S1 i-1 and the ith first scan line S1 i. In addition, during thesecond period T2, a voltage of a reference power source Vref is suppliedto the data lines D.

The driving method will be described in conjunction with FIGS. 2 and 6.During the first period T1, a voltage of the data signal DS is stored ineach of the pixels PXL. Then, the first transistor M1 supplies, to theorganic light emitting diode OLED, a current (e.g., a predeterminedcurrent) corresponding to a difference between a voltage of the firstdriving power source, applied to the first node N1, and a voltage of thedata signal DS, applied to the second node N2.

During a partial period of the second period T2, an emission controlsignal is supplied to the ith emission control line Ei. When theemission control signal is supplied to the ith emission control line Ei,the fifth transistor M5 is turned off. Then, the pixel PXL is set to thenon-emission state.

After that, a scan signal is supplied to the ith first scan line S1 i.When the scan signal is supplied to the ith first scan line S1 i, thesecond transistor M2 is turned on. When the second transistor M2 isturned on, the voltage of the reference power source Vref is suppliedfrom the data line Dm to the first node N1. Then, characteristic curvesof the first transistor M1 are changed, and accordingly, the displayquality of the organic light emitting display device can be improved.

For example, characteristics of the first transistor M1 are set to aspecific state as shown in FIG. 7, corresponding to the voltage of thefirst driving power source ELVDD, applied to the first node N1, during aperiod in which the pixel PXL emits light. When the characteristics ofthe first transistor M1 are set to the specific state during one frameperiod, an image with a desired luminance may not be displayedcorresponding to the data signal DS during at least an early period of anext frame period.

When the organic light emitting display device is driven at the seconddriving frequency, one frame period 1F is set relatively widely (e.g.,relative to when the organic light emitting display device is driven atthe first driving frequency). In an embodiment, when the first drivingfrequency is set to 60 Hz, the one frame period 1F may be set to 1/60 s(second). When the second driving frequency is set to 10 Hz, the oneframe period 1F may be set to 1/10 s (second). Therefore, when thecharacteristics of the first transistor M1 are fixed to the specificstate during one frame period when the organic light emitting displaydevice is driven at the second driving frequency, flickers may begenerated.

On the other hand, in the present disclosure, when the voltage of thereference power source Vref is supplied to the first electrode of thefirst transistor M1, the characteristics of the first transistor M1 arechanged. Actually, in the present disclosure, the voltage of thereference power source Vref is periodically supplied to the firstelectrode of the first transistor M1 during the second period T2, andaccordingly, it is possible to prevent the characteristics of the firsttransistor M1 from being fixed to the specific state.

To this end, the voltage of the reference power source Vref may be setto a specific voltage within a voltage range of the data signal. Inaddition, the voltage of the reference power source Vref may be set to avoltage different from that of the first driving power source ELVDD, forexample, a voltage higher than that of the first driving power sourceELVDD. For example, the voltage of the reference power source Vref maybe set to a voltage equal to or greater than a half of the voltage rangeof the data signal, for example, a data signal of a black gray level.

When scan signals are sequentially supplied to the first scan lines S11to S1 n and emission control signals are sequentially supplied to theemission control lines E1 to En during the period in which the organiclight emitting display device is driven at the second driving frequency,a driving condition in which the organic light emitting display deviceis driven at the second driving frequency may be similar or identical tothat in which the organic light emitting display device is driven at thefirst driving frequency. Accordingly, the display quality of the organiclight emitting display device can be improved.

For example, when the first driving frequency is set to 60 Hz, thepixels PXL are set to the non-emission state sixty times in one second.In addition, when the second driving frequency is set to 10 Hz, thepixels PXL are set to the non-emission state ten times in one second.When numbers of times of the pixels PXL set to the non-emission stateare differently set when the organic light emitting display device isdriven at the first driving frequency and the second driving frequency,a luminance difference, and/or the like may be recognized by an observereven when the same image is displayed.

On the other hand, when an emission control signal is supplied fivetimes to each of the emission control lines E1 to En during the secondperiod T2 when the organic light emitting display device is driven atthe second driving frequency (e.g., 10 Hz), a number of times of thepixels set to the non-emission state is set identically to a number oftimes of the pixels set to the non-emission state when the organic lightemitting display device is driven at the first driving frequency. Thatis, in the embodiment of the present disclosure, the driving conditionin which the organic light emitting display device is driven at thesecond driving frequency is similar or identical to the drivingcondition in which the organic light emitting display device is drivenat the first driving frequency, so that the display quality of theorganic light emitting display device can be improved. In addition, whenthe organic light emitting display device is driven at the seconddriving frequency, the data signal DS is supplied to the data lines Dduring (e.g., only during) the first period T1, and accordingly, thepower consumption of the organic light emitting display device can bereduced or minimized.

FIG. 8 is a waveform diagram illustrating gate start pulses supplied tothe first scan driver and the second scan driver.

Referring to FIG. 8, when the organic light emitting display device isdriven at the first driving frequency, the same number of scan signalsare supplied to the first scan lines S11 to S1 n and the second scanlines S21 to S2 n as shown in FIG. 5. Therefore, when the organic lightemitting display device is driven at the first driving frequency, anumber of first gate start pulses GSP1 supplied from the timingcontroller 140 to the first scan driver 110 is set equal to that ofsecond gate start pulses GSP2 supplied from the timing controller 140 tothe second scan driver 120.

When the organic light emitting display device is driven at the secondfrequency, different numbers of scan signals are supplied to the firstscan lines S11 to S1 n and the second scan lines S21 o S2 n as shown inFIG. 6. Therefore, when the organic light emitting display device isdriven at the second frequency, a number of first gate start pulses GSP1supplied from the timing controller 140 to the first scan driver 110 isset different from that of second gate start pulses GSP2 supplied fromthe timing controller 140 to the second scan driver 120. In other words,when the organic light emitting display device is driven at the secondfrequency, l (l is a natural number of 2 or more) first gate startpulses GSP1 are supplied to the first scan driver 110, and p (p is anatural number smaller than l) second start pulses GSP2 are supplied tothe second scan driver 120.

FIG. 9 is a circuit diagram illustrating another embodiment of the pixelshown in FIG. 1. In FIG. 9, components identical to those of FIG. 2 aredesignated by like reference numerals, and their detailed descriptionsmay not be repeated.

Referring to FIG. 9, the pixel PXL according to the embodiment of thepresent disclosure includes an organic light emitting diode OLED and apixel circuit 201 for controlling the amount of current supplied to theorganic light emitting diode OLED.

An anode electrode of the organic light emitting diode OLED is coupledto the pixel circuit 201, and a cathode electrode of the organic lightemitting diode OLED is coupled to the second driving power source ELVSS.The organic light emitting diode OLED generates light with a luminance(e.g., a predetermined luminance) corresponding to the amount of currentsupplied from the pixel circuit 201.

The pixel circuit 201 controls the amount of current flowing from thefirst driving power ELVDD to the second driving power ELVSS via theorganic light emitting diode OLED, corresponding to a data signal. Tothis end, the pixel circuit 201 includes a first transistor M1, a secondtransistor M2, a third transistor M3′, a fourth transistor M4′, a fifthtransistor M5, and a storage capacitor Cst.

The third transistor M3′ is coupled between a second electrode of thefirst transistor M1 and a second node N2. In addition, a gate electrodeof the third transistor M3′ is coupled to an ith second scan line S2 i.The third transistor M3′ is turned on when a scan signal is supplied tothe ith second scan line S2 i to allow the second electrode of the firsttransistor M1 and the second node N2 to be electrically coupled to eachother. Therefore, when the third transistor M3′ is turned on, the firsttransistor M1 is diode-coupled.

The fourth transistor M4′ is coupled between the second node N2 and theinitialization power source Vint. In addition, a gate electrode of thefourth transistor M4′ is coupled to an (i−1)th second scan line S2 i-1.The fourth transistor M4′ is turned on when a scan signal is supplied tothe (i−1)th second scan line S2 i-1 to supply the voltage of theinitialization power source Vint to the second node N2.

The third transistor M3′ and the fourth transistor M4′ are formed asN-type transistors. In an embodiment, the third transistor M3′ and thefourth transistor M4′ may be formed as N-type oxide semiconductortransistors.

The oxide semiconductor transistor can be formed through a lowtemperature process, and has a charge mobility lower than that of thepoly-silicon semiconductor transistor. That is, the oxide semiconductortransistor has excellent off-current characteristics. Thus, when thethird transistor M3′ and the fourth transistor M4′ are formed as oxidesemiconductor transistors, leakage current from the second node N2 canbe reduced or minimized, and accordingly, the display quality of theorganic light emitting display device can be improved.

The pixel shown in FIG. 9 is configured identically to the pixel shownin FIG. 2 except that the third transistor M3′ and the fourth transistorM4′ are formed as N-type transistors. In addition, the pixel shown inFIG. 9 is operated identically to the pixel shown in FIG. 2 except that,as shown in FIG. 10, scan signals supplied to the second scan lines S2are set to a high voltage (i.e., the gate-on voltage) such that thethird transistor M3′ and the fourth transistor M4′, which are formed asN-type transistors, can be turned on. Therefore, a detailed descriptionof said elements may not be repeated.

FIG. 11 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 9 is driven at the first drivingfrequency. The driving method of FIG. 11 is substantially identical tothat of FIG. 5 except that only the polarity of scan signals supplied tothe second scan lines S21 to S2 n is changed therefore, the drivingmethod of FIG. 11 will be briefly described.

Referring to FIG. 11, when the organic light emitting display device isdriven at the first driving frequency, scan signals are sequentiallysupplied to the first scan lines S11 to S1 n and the second scan linesS21 to S2 n during one frame period 1F. In addition, when the organiclight emitting display device is driven at the first driving frequency,emission control signals are sequentially supplied to the emissioncontrol lines E1 to En during the one frame period 1F.

Then, a voltage corresponding to a data signal is stored in each of thepixels PXL, and accordingly, the pixel unit 10 can display an image(e.g., a predetermined image).

FIG. 12 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 9 is driven at the second drivingfrequency. The driving method of FIG. 12 is substantially identical tothat of FIG. 6 except that only the polarity of scan signals supplied tothe second scan lines S21 to S2 n is changed; therefore, the drivingmethod of FIG. 12 will be briefly described.

Referring to FIG. 12, scan signals are sequentially supplied to thefirst scan lines S11 to S1 n and the second scan lines S21 to S2 nduring a first period T1 of one frame period 1F. In addition, emissioncontrol signals are sequentially supplied to the emission control linesE1 to En during the first period T1. Then, a voltage corresponding to adata signal DS is stored in each of the pixels PXL during the firstperiod T1.

A plurality of scan signals are supplied to each of the first scan linesS11 to S1 n during a second period T2 of the one frame period 1F. In anembodiment, a scan signal may be sequentially supplied several times toeach of the first scan lines S11 to S1 n during the second period T2.

A plurality of emission control signal are supplied to each of theemission control lies E1 to En during the second period T2. Here, anemission control signal supplied to an ith emission control line Ei maybe supplied to overlap with scan signals supplied to an (i−1) the firstscan line S1 i-1 and an ith first scan line S1 i. In addition, a voltageof a reference voltage Vref is supplied to the data lines D during thesecond period T2.

Here, when the plurality of scan signals are supplied to each of thefirst scan lines S11 to S1 n during the second period T2,characteristics of the first transistor M1 included in each of thepixels PXL are periodically changed, and according, the display qualityof the organic light emitting display device can be improved.

FIG. 13 is a circuit diagram illustrating still another embodiment ofthe pixel shown in FIG. 1. In FIG. 13, components identical to those ofFIG. 2 are designated by like reference numerals, and their detaileddescriptions may not be repeated.

Referring to FIG. 13, the pixel according to the embodiment of thepresent disclosure includes an organic light emitting diode OLED and apixel circuit 202 for controlling the amount of current supplied to theorganic light emitting diode OLED.

An anode electrode of the organic light emitting diode OLED is coupledto the pixel circuit 202, and a cathode electrode of the organic lightemitting diode OLED is coupled to the second driving power source ELVSS.The organic light emitting diode OLED generates light with a luminance(e.g., a predetermined luminance) corresponding to the amount of currentsupplied from the pixel circuit 202.

The pixel circuit 202 controls the amount of current flowing from thefirst driving power source ELVDD to the second driving power sourceELVSS via the organic light emitting diode OLED, corresponding to a datasignal. To this end, the pixel circuit 202 includes first to seventhtransistors M1 to M7 and a storage capacitor Cst.

The sixth transistor M6 is coupled between a second electrode of thefirst transistor M1 and the anode electrode of the organic lightemitting diode OLED. In addition, a gate electrode of the sixthtransistor M6 is coupled to an emission control line Ei. The sixthtransistor M6 is turned off when an emission control signal is suppliedto the emission control line Ei, and is turned on otherwise.

The seventh transistor M7 is coupled between the anode electrode of theorganic light emitting diode OLED and the initialization power sourceVint. In addition, a gate electrode of the seventh transistor M7 iscoupled to an ith first scan line S1 i. The seventh transistor M7 isturned on when a scan signal is supplied to the ith first scan line S1 ito supply the voltage of the initialization power source Vint to theanode electrode of the organic light emitting diode OLED.

If the voltage of the initialization power source Vint is supplied tothe anode electrode of the organic light emitting diode OLED, aparasitic capacitor (hereinafter, referred to as an “organic capacitorColed”) of the organic light emitting diode OLED is discharged. When theorganic capacitor Coled is discharged, the black expression ability ofthe pixel PXL is improved.

For example, a voltage (e.g., a predetermined voltage) is charged in theorganic capacitor Coled, corresponding to a current supplied from thefirst transistor M1, during a previous frame period. When the organiccapacitor Coled is charged, the organic light emitting diode OLED mayeasily emit light even at a low current.

A black data signal may be supplied in a current frame period. When theblack data signal is supplied, the first transistor M1 is to ideallysupply no current to the organic light emitting diode OLED. However, aleakage current (e.g., a predetermined leakage current) is supplied tothe organic light emitting diode OLED even when the black data signal issupplied. At this time, when the organic capacitor Coled is in acharge-state, light is minutely emitted from the organic light emittingdiode OLED, and therefore, the black expression ability of the pixel PXLis deteriorated.

On the other hand, in the present disclosure, when the organic capacitorColed is discharged by the initialization power source Vint, the organiclight emitting diode OLED is set to the non-emission state by leakagecurrent. That is, in the present disclosure, the organic capacitor Coledis discharged using the initialization power source Vint, andaccordingly, the black expression ability of the pixel PXL can beimproved (e.g., the pixel may express deeper and darker blacks).

An operating process of the pixel PXL will be described in conjunctionwith FIGS. 13 and 3. First, an emission control signal is supplied tothe emission control line Ei. When the emission control signal issupplied to the emission control line Ei, the fifth transistor M5 andthe sixth transistor M6 are turned off. When the fifth transistor M5 isturned off, the electrical coupling between a first node N1 and thefirst driving power source ELVDD is interrupted. When the sixthtransistor M6 is turned off, the electrical coupling between the firsttransistor M1 and the organic light emitting diode OLED is interrupted.Therefore, the pixel PXL is set to the non-emission state during aperiod in which the emission control signal is supplied to the emissioncontrol line Ei.

After that, a scan signal is supplied to an (i−1)th second scan line S2i-1. When the scan signal is supplied to the (i−1)th second scan line S2i-1, the fourth transistor M4 is turned on. When the fourth transistorM4 is turned on, the voltage of the initialization power source Vint issupplied to a second node N2.

After the voltage of the initialization power source Vint is supplied tothe second node N2, scan signals are supplied to an ith first scan lineS1 i and an ith second scan line S2 i. When the scan signal is suppliedto the ith second scan line S2 i, the third transistor M3 is turned on.When the third transistor M3 is turned on, the first transistor M1 isdiode-coupled.

If the scan signal is supplied to the ith first scan line S1 i, thesecond transistor M2 and the seventh transistor M7 are turned on. Whenthe seventh transistor M7 is turned on, the voltage of theinitialization power source Vint is supplied to the anode electrode ofthe organic light emitting diode OLED. When the second transistor M2 isturned on, a data signal DS from a data line Dm is supplied to the firstnode N1. At this time, because the second node N2 is initialized to thevoltage of the initialization power source Vint, which is lower than thevoltage of the data signal DS, the first transistor M1 is turned on.

If the first transistor M1 is turned on, the data signal DS supplied tothe first node N1 is supplied to the second node N2 via thediode-coupled first transistor M1. Then, a voltage corresponding to thedata signal DS and a threshold voltage of the first transistor M1 isapplied to the second node N2. At this time, the storage capacitor Cststores a voltage of the second node N2.

The supply of the emission control signal to the emission control lineEi is stopped after the voltage corresponding to the data signal DS andthe threshold voltage of the first transistor M1 is stored in thestorage capacitor Cst. When the supply of the emission control signal tothe emission control line Ei is stopped, the fifth transistor M5 and thesixth transistor M6 are turned on.

When the fifth transistor M5 is turned on, the first driving powersource ELVDD and the first node N1 are electrically coupled to eachother. At this time, the first transistor M1 controls the amount ofcurrent flowing from the first driving power source ELVDD to the seconddriving power source ELVDD via the organic light emitting diode OLED,corresponding to the voltage of the second node N2. Then, the organiclight emitting diode OLED generates light with a luminance correspondingto the amount of the current. Actually, the pixel PXL of the presentdisclosure is driven while repeating the above-described process.

The pixel shown in FIG. 13 is driven at the first driving frequency andthe second driving frequency, corresponding to the driving waveforms ofFIGS. 5 and 6. A driving method of the pixel PXL shown in FIG. 13 whenthe pixel PXL is driven at the first driving frequency and the seconddriving frequency is substantially identical to that of the pixel PXLshown in FIG. 2, and therefore, its detailed description may not berepeated.

The first to seventh transistors M1 to M7 are formed as P-typetransistors. In an embodiment, the first to seventh transistors M1 to M7may be formed as P-type poly-silicon semiconductor transistors.

FIG. 14 is a circuit diagram illustrating still another embodiment ofthe pixel shown in FIG. 1. In FIG. 14, components identical to those ofFIG. 13 are designated by like reference numerals, and their detaileddescriptions may not be repeated.

Referring to FIG. 14, the pixel PXL according to the embodiment of thepresent disclosure includes an organic light emitting diode OLED and apixel circuit 203 for controlling the amount of current supplied to theorganic light emitting diode OLED.

An anode electrode of the organic light emitting diode OLED is coupledto the pixel circuit 203, and a cathode electrode of the organic lightemitting diode OLED is coupled to the second driving power source ELVSS.The organic light emitting diode OLED generates light with a luminance(e.g., a predetermined luminance) corresponding to the amount of currentsupplied from the pixel circuit 203.

The pixel circuit 203 controls the amount of current flowing from thefirst driving power source ELVDD to the second driving power sourceELVDD via the organic light emitting diode OLED, corresponding to a datasignal. To this end, the pixel circuit 203 includes a first transistorM1, a second transistor M2, a third transistor M3′, a fourth transistorM4′, a fifth transistor M5, a sixth transistor M6, a seventh transistorM7′, and a storage capacitor Cst.

The third transistor M3′ is coupled between a second node of the firsttransistor M1 and a second node N2. In addition, a gate electrode of thethird transistor M3′ is coupled to an ith second scan line S2 i. Thethird transistor M3′ is turned on when a scan signal is supplied to theith second scan line S2 i to allow the second electrode of the firsttransistor M1 and the second node N2 to be electrically coupled to eachother. Therefore, when the third transistor M3′ is turned on, the firsttransistor M1 is diode-coupled.

The fourth transistor M4′ is coupled between the second node N2 and theinitialization power source Vint. In addition, a gate electrode of thefourth transistor M4′ is coupled to an (i−1)th second scan line S2 i-1.The fourth transistor M4′ is turned on when a scan signal is supplied tothe (i−1)th second scan line S2 i-1 to supply the voltage of theinitialization power source Vint to the second node N2.

The seventh transistor M7′ is coupled between the anode electrode of theorganic light emitting diode OLED and the initialization power sourceVint. In addition, a gate electrode of the seventh transistor M7′ iscoupled to an emission control line Ei. The seventh transistor M7′ isturned on when an emission control signal is supplied to the emissioncontrol line Ei to supply the voltage of the initialization power sourceVint to the anode electrode of the organic light emitting diode OLED.

The third transistor M3′, the fourth transistor M4′, and the seventhtransistor M7′ are formed as N-type transistors. In an embodiment, thethird transistor M3′, the fourth transistor M4′, and the seventhtransistor M7′ may be formed as N-type oxide semiconductor transistors.When the third transistor M3′ and the fourth transistor M4′ are formedas oxide semiconductor transistors, leakage current from the second nodeN2 can be reduced or minimized. In addition, when the seventh transistorM7′ is formed as an oxide semiconductor transistor, leakage currentbetween the anode electrode of the organic light emitting diode OLED andthe initialization power source Vint can be reduced or minimized.

An operating process of the pixel PXL shown in FIG. 14 is substantiallysimilar or identical to that of the pixel PXL shown in FIG. 13 exceptthat the third transistor M3′, the fourth transistor M4′, and theseventh transistor M7′ are formed as N-type transistors. In other words,a driving method of the pixel PXL shown in FIG. 14 is similar oridentical to that of the pixel PXL shown in FIG. 13 except that, asshown in FIG. 10, scan signals supplied to the second scan lines S areset to a high voltage (i.e., the gate-on voltage) such that the thirdtransistor M3′ and the fourth transistor M4′, which are formed as N-typetransistors, can be turned on. Therefore, a detailed description of saidelements may not be repeated.

In FIG. 14, it is illustrated that the seventh transistor M7′ is coupleto the emission control line Ei, but the embodiment of the presentdisclosure is not limited thereto. In an embodiment, the seventhtransistor M7′ may be coupled to an ith third scan line S3 iadditionally formed as shown in FIG. 15. In this case, a third scandriver for supplying scan signals to third scan lines S3 may beadditionally provided to the organic light emitting display device.

As shown in FIGS. 16A and 16B, a scan signal (gate-on voltage of a highlevel) is supplied to the ith third scan line S3 i to overlap with theemission control signal supplied to the emission control line Ei. Whenthe scan signal is supplied to the ith third scan line S3 i, the seventhtransistor M7′ is turned on, so that the voltage of the initializationpower source Vint is supplied to the anode electrode of the organiclight emitting diode OLED.

FIG. 17 is a circuit diagram illustrating still another embodiment ofthe pixel shown in FIG. 1. In FIG. 17, components identical to those ofFIG. 14 are designated by like reference numerals, and their detaileddescriptions may not be repeated.

Referring to FIG. 17, the pixel PXL according to the embodiment of thepresent disclosure includes an organic light emitting diode OLED and apixel circuit 204 for controlling the amount of current supplied to theorganic light emitting diode OLED.

An anode electrode of the organic light emitting diode OLED is coupledto the pixel circuit 204, and a cathode electrode of the organic lightemitting diode OLED is coupled to the second driving power source ELVSS.The organic light emitting diode OLED generates light with a luminance(e.g., a predetermined luminance) corresponding to the amount of currentsupplied from the pixel circuit 204.

The pixel circuit 204 controls the amount of current flowing from thefirst driving power source ELVDD to the second driving power sourceELVSS via the organic light emitting diode OLED, corresponding to a datasignal. To this end, the pixel circuit 204 includes a first transistorM1, a second transistor M2′, a third transistor M3′, a fourth transistorM4′, a fifth transistor M5, a sixth transistor M6, a seventh transistorM7′, and a storage capacitor Cst.

The second transistor M2′ is coupled between a data line Dm and a firstnode N1. In addition, a gate electrode of the second transistor M2′ iscoupled to an ith first scan line S1 i. The second transistor M2′ isturned on when a scan signal is supplied to the ith first scan line S1 ito allow the data line Dm and the first node N1 to be electricallycoupled to each other.

The second transistor M2′ may be formed as an N-type oxide semiconductortransistor. When the second transistor M2′ may be formed as an N-typeoxide semiconductor transistor, leakage current between the data line Dmand the first node N1 can be reduced or minimized, and accordingly, thedisplay quality of the organic light emitting display device can beimproved.

Additionally, an operating process of the pixel PXL shown in FIG. 17 issubstantially similar or identical to that of the pixel PXL shown inFIG. 14 except that the second transistor M2′ is formed as an N-typetransistor. In other words, a driving method of the pixel PXL shown inFIG. 17 is similar or identical to that of the pixel PXL shown in FIG.14 except that, as shown in FIG. 18, scan signals supplied to the secondscan lines S are set to a high voltage (i.e., the gate-on voltage) suchthat the second transistor M2′ formed as an N-type transistor can beturned on. Therefore, a detailed description of said elements may not berepeated.

FIG. 19 is a circuit diagram illustrating still another embodiment ofthe pixel shown in FIG. 1. For convenience of description, a pixel thatis located on an ith horizontal line and is coupled to an mth data lineDm is illustrated in FIG. 19.

Referring to FIG. 19, the pixel PXL according to the embodiment of thepresent disclosure includes an organic light emitting diode OLED and apixel circuit 205 for controlling the amount of current supplied to theorganic light emitting diode OLED.

An anode electrode of the organic light emitting diode OLED is coupledto the pixel circuit 205, and a cathode electrode of the organic lightemitting diode OLED is coupled to the second driving power source ELVSS.The organic light emitting diode OLED generates light with a luminance(e.g., a predetermined luminance) corresponding to the amount of currentsupplied from the pixel circuit 205.

The pixel circuit 205 controls the amount of current flowing from thefirst driving power source ELVDD to the second driving power sourceELVSS via the organic light emitting diode OLED, corresponding to a datasignal. To this end, the pixel circuit 205 includes eleventh tosixteenth transistors M11 to M16 and a storage capacitor Cst.

A first electrode of the eleventh transistor (or driving transistor) M11is coupled to the first driving power source ELVDD via the sixteenthtransistor M16, and a second electrode of the eleventh transistor M11 iscoupled to the anode electrode of the organic light emitting diode OLED.In addition, a gate electrode of the eleventh transistor M11 is coupledto an eleventh node N11. The eleventh transistor M11 controls the amountof the current flowing from the first driving power source ELVDD to thesecond driving power source ELVSS via the organic light emitting diodeOLED, corresponding to a voltage of the eleventh node N11.

The twelfth transistor M12 is coupled between a data line Dm and atwelfth node N12. In addition, a gate electrode of the twelfthtransistor M12 is coupled to an ith first scan line S1 i. The twelfthtransistor M12 is turned on when a scan signal is supplied to the ithfirst scan line S1 i. To this end, the scan signal is set to the gate-onvoltage.

The thirteenth transistor M13 is coupled between the twelfth node N12and the anode electrode of the organic light emitting diode OLED. Inaddition, a gate electrode of the thirteenth transistor M13 is coupledto an (i−1)th emission control line Ei-1. The thirteenth transistor M13is turned off when an emission control signal is supplied to the (i−1)themission control line Ei-1, and is turned on when the emission controlsignal is not supplied. To this end, the emission control signal is setto the gate-off voltage.

The fourteenth transistor M14 is coupled between the eleventh node N11and the first electrode of the eleventh transistor M11. In addition, agate electrode of the fourteenth transistor M14 is coupled to an ithsecond scan line S2 i. The fourteenth transistor M14 is turned on when ascan signal is supplied to the ith second scan line S2 i.

The fifteenth transistor M15 is coupled between an initialization powersource Vint′ and the anode electrode of the organic light emitting diodeOLED. In addition, a gate electrode of the fifteenth transistor M15 iscoupled to the ith first scan line S1 i. The fifteenth transistor M15 isturned on when the scan signal is supplied to the ith first scan line S1i. In addition, a voltage of the initialization power source Vint′ isset such that organic light emitting diode OLED is turned off.

The sixteenth transistor M16 is coupled between the first driving powersource ELVDD and the first electrode of the eleventh transistor M11. Inaddition, a gate electrode of the sixteenth transistor M16 is coupled toan ith emission control line Ei. The sixteenth transistor M16 is turnedoff when an emission control signal is supplied to the ith emissioncontrol line, and is turned on when the emission control signal is notsupplied.

The storage capacitor Cst is coupled between the eleventh node N11 andthe twelfth node N12 that is a common node between the twelfthtransistor M12 and the thirteenth transistor M13. The storage capacitorCst stores a voltage corresponding to the data signal and a thresholdvoltage of the eleventh transistor M11.

The eleventh to sixteenth transistors M11 to M16 are formed as N-typetransistors. In an embodiment, the eleventh to sixteenth transistors M11to M16 may be formed as N-type poly-silicon semiconductor transistors orN-type oxide semiconductor transistors.

FIG. 20 is a waveform diagram illustrating an embodiment of a drivingmethod of the pixel shown in FIG. 19.

Referring to FIG. 20, first, an emission control signal is supplied tothe (i−1)th emission control line Ei-1. When the emission control signalis supplied to the (i−1)th emission control line Ei-1, the thirteenthtransistor M13 is turned off. When the thirteenth transistor M13 isturned off, the electrical coupling between the twelfth node N12 and theanode electrode of the organic light emitting diode OLED is interrupted.

After that, scan signals are supplied to the ith first scan line S1 iand the ith second scan line S2 i. When the scan signal is supplied tothe ith first scan line S1 i, the twelfth transistor M12 and thefifteenth transistor M15 are turned on. In addition, when the scansignal is supplied to the ith second scan line S2 i, the fourteenthtransistor M14 is turned on.

When the twelfth transistor M12 is turned on, the data line Dm and thetwelfth node N12 are electrically coupled to each other. Then, a datasignal DS from the data line Dm is supplied to the twelfth node N12.

When the fourteenth transistor M14 is turned on, the eleventh node N11and the first electrode of the eleventh transistor M11 are electricallycoupled to each other. At this time, the eleventh node N11 isinitialized to a voltage of the first driving power source ELVDD. Inaddition, when the fourteenth transistor M14 is turned on, the eleventhtransistor M11 is diode-coupled.

When the fifteenth transistor M15 is turned on, a voltage of theinitialization power source Vint′ is supplied to the anode electrode ofthe organic light emitting diode OLED, and accordingly, the anodeelectrode of the organic light emitting diode OLED is initialized to thevoltage of the initialization power source Vint′. At this time, theorganic light emitting diode OLED is set to the non-emission state.

After that, an emission control signal is supplied to the ith emissioncontrol line Ei. When the emission control signal is supplied to the ithemission control line Ei, the sixteenth transistor M16 is turned off.When the sixteenth transistor M16 is turned off, the electrical couplingbetween the first driving power source ELVDD and the first electrode ofthe eleventh transistor M11 is interrupted.

At this time, because the second electrode of the eleventh transistorM11 is set to the voltage of the initialization power source Vint′, theeleventh node N11 is set to a voltage obtained by adding a thresholdvoltage of the eleventh transistor M11 to the voltage of theinitialization power source Vint′. Here, because the twelfth node N12 isset to a voltage of the data signal DS, a voltage corresponding to thedata signal DS and the threshold voltage of the eleventh transistor M11is stored in the storage capacitor Cst.

After the voltage corresponding to the data signal DS and the thresholdvoltage of the eleventh transistor M11 is stored in the storagecapacitor Cst, the supply of the emission control signal to the (i−1)themission control line Ei-1 and the supply of the emission control signalto the ith emission control line Ei are sequentially stopped.

When the supply of the emission control signal to the (i−1)th emissioncontrol line Ei-1 is stopped, the thirteenth transistor M13 is turnedon. When the thirteenth transistor M13 is turned on, the twelfth nodeN12 and the anode electrode of the organic light emitting diode OLED areelectrically coupled to each other.

When the supply of the emission control signal to the ith emissioncontrol line Ei is stopped, the sixteenth transistor M16 is turned on.When the sixteenth transistor M16 is turned on, the voltage of the firstdriving power source ELVDD is supplied to the first electrode of theeleventh transistor M11. At this time, the eleventh transistor M11controls the amount of current flowing from the first driving powersource ELVDD to the second driving power source ELVSS via the organiclight emitting diode OLED, corresponding to a voltage of the eleventhnode N11. Actually, the pixel PXL shown in FIG. 19 is driven whilerepeating the above-described process.

FIG. 21 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 19 is driven at the first drivingfrequency.

Referring to FIG. 21, when the organic light emitting display device isdriven at the first driving frequency, scan signals are sequentiallysupplied to the first scan lines S11 to S1 n and the second scan linesS21 to S2 n during one frame period 1F. Here, a scan signal supplied toan ith first scan line S1 i overlaps with that supplied to an ith secondscan line S2 i.

In addition, when the organic light emitting display device is driven atthe first driving frequency, emission control signals are sequentiallysupplied to the emission control lines E1 to En during the one frameperiod 1F. Here, an emission control signal supplied to an ith emissioncontrol line Ei is supplied to overlap with the scan signal supplied tothe ith first scan line S1 i during a partial period and overlap with ascan signal supplied to an (i+1)th first scan line S1 i+1. A data signalDS is supplied to the data lines Dm to be synchronized with the scansignals.

Then, as described in FIGS. 19 and 20, each of the pixels PXL generateslight with a luminance (e.g., a predetermined luminance) correspondingto the data signal DS.

FIG. 22 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 19 is driven at the second drivingfrequency.

Referring to FIG. 22, when the organic light emitting display device isdriven at the second driving frequency, one frame period 1F is dividedin a first period T1 and a second period T2. Here, the second period T2may be set as a period wider than the first period T1.

During the first period T1, scan signals are sequentially supplied tothe first scan lines S11 to S1 n and the second scan lines S21 to S2 n.Here, a scan signal supplied to the ith first scan line S1 i overlapswith the ith second scan line S2 i.

In addition, during the first period T1, emission control signals aresequentially supplied to the emission control lines E1 to En. Here, anemission control signal supplied to the ith emission control line Ei issupplied to overlap with the scan signal supplied to the ith first scanline S1 i during a partial period and overlap with a scan signalsupplied to the (i+1)th first scan line S1 i+1. A data signal DS issupplied to the data lines D to be synchronized to the scan signals.Then, a voltage corresponding to the data signal DS is stored in each ofthe pixels PXL during the first period T1, and accordingly, each of thepixels PXL generates light with a corresponding luminance (e.g., apredetermined luminance).

During the second period T2, a plurality of scan signals are supplied toeach of the first scan lines S11 to S1 n. Here, the scan signalssupplied to each of the first scan lines S11 to S1 n may be supplied forevery set or predetermined period. In an embodiment, during the secondperiod T2, scan signals may be supplied several times to the first scanlines S11 to S1 n while being sequentially repeated.

During the second period T2, a plurality of emission control signals aresupplied to each of the emission control lines E1 to En. Here, anemission control signal supplied to the ith emission control line Ei issupplied to overlap with the scan signal supplied to the ith first scanline S1 i during a partial period and overlap with the scan signalsupplied to the (i+1)th first scan line S1 i+1. In addition, a voltageof a reference power source Vref is supplied to the data lines D duringthe second period T2.

The driving method will be described in conjunction with FIGS. 19 and22. During the first period T1, a voltage of the data signal DS isstored in each of the pixels PXL. Then, the eleventh transistor M11supplies, to the organic light emitting diode OLED, a current (e.g., apredetermined current) corresponding to a difference between a voltageof the data signal, applied to the eleventh node N11, and a voltage ofthe first driving power source ELVDD, applied to the first electrodethereof.

During a partial period of the second period T2, emission controlsignals are supplied to the (i−1)th emission control line (Ei-1) and theith emission control line Ei, and accordingly, the thirteenth transistorM13 and the sixteenth transistor M16 are turned off. Then, the pixel PXLis set to the non-emission state.

After that, a scan signal is supplied to the ith first scan line S1 i.When the scan signal is supplied to the ith first scan line S1 i, thetwelfth transistor M12 and the fifteenth transistor M15 are turned on.When the fifteenth transistor M15 is turned on, the anode electrode ofthe organic light emitting diode OLED is initialized to a voltage of theinitialization power source Vint′.

When the twelfth transistor M12 is turned on, the voltage of thereference power source Vref is supplied to the twelfth node N12. Whenthe voltage of the reference power source Vref is supplied to thetwelfth node N12, a voltage of the eleventh node N11 is changed bycoupling of the storage capacitor Cst. At this time, characteristiccurves of the eleventh transistor M11 are changed corresponding to adifference between the voltage applied to the eleventh node N11 and thevoltage of the first driving power source ELVDD. That is, in theembodiment of the present disclosure, it is possible to preventcharacteristics of the eleventh transistor M11 from being fixed to aspecific state, and accordingly, the display quality of the organiclight emitting display device can be improved.

To this end, the voltage of the reference power source Vref may be setto a specific voltage within a voltage range of the data signal. Inaddition, the voltage of the reference power source Vref may be set to avoltage different from that of the first driving power source ELVDD.

When scan signals are sequentially supplied to the first scan lines S11to S1 n and emission control signals are sequentially supplied to theemission control lines E1 to En during the period in which the organiclight emitting display device is driven at the second driving frequency,a driving condition in which the organic light emitting display deviceis driven at the second driving frequency may be similar or identical tothat in which the organic light emitting display device is driven at thefirst driving frequency. Accordingly, the display quality of the organiclight emitting display device can be improved.

For example, when the first driving frequency is set to 60 Hz, thepixels PXL are set to the non-emission state sixty times in one second.In addition, when the second driving frequency is set to 10 Hz, thepixels PXL are set to the non-emission state ten times in one second.When numbers of times of the pixels PXL set to the non-emission stateare differently set when the organic light emitting display device isdriven at the first driving frequency and the second driving frequency,a luminance difference, and/or the like may be recognized by an observereven when the same image is displayed.

On the other hand, when an emission control signal is supplied fivetimes to each of the emission control lines E1 to En during the secondperiod T2 when the organic light emitting display device is driven atthe second driving frequency (e.g., 10 Hz), a number of times of thepixels set to the non-emission state is set identically to a number oftimes of the pixels set to the non-emission state when the organic lightemitting display device is driven at the first driving frequency. Thatis, in the embodiment of the present disclosure, the driving conditionin which the organic light emitting display device is driven at thesecond driving frequency is similar or identical to the drivingcondition in which the organic light emitting display device is drivenat the first driving frequency, so that the display quality of theorganic light emitting display device can be improved. In addition, whenthe organic light emitting display device is driven at the seconddriving frequency, the data signal DS is supplied to the data lines Dduring (e.g., only during) the first period T1, and accordingly, thepower consumption of the organic light emitting display device can bereduced or minimized.

FIG. 23 is a diagram schematically illustrating an organic lightemitting display device according to another embodiment of the presentdisclosure. In FIG. 23, components identical to those of FIG. 1 aredesignated by like reference numerals, and their detailed descriptionsmay not be repeated.

Referring to FIG. 23, the organic light emitting display deviceaccording to the embodiment of the present disclosure includes a pixelunit 100, a first scan driver 110′, a second scan driver 120′, a thirdscan driver 170, a data driver 130′, a timing controller 140′, a hostsystem 150, and an emission driver 160.

The timing controller 140′ supplies a gate start pulse GSP1, GSP2, orGSP3 and clock signals CLK to the first scan driver 110′, the secondscan driver 120′, and the third scan driver 170, based on timing signalsVsync, Hsync, DE, and CLK.

A first gate start pulse GSP1 controls a first timing of a scan signalsupplied from the first scan driver 110′. Clock signals CLK are used toshift (e.g., shift in time) the first gate start pulse GSP1.

A second gate start pulse GSP2 controls a first timing of a scan signalsupplied from the second scan driver 120′. Clock signals CLK are used toshift (e.g., shift in time) the second gate start pulse GSP2.

A third gate start pulse GSP3 controls a first timing of a scan signalsupplied from the third scan driver 170. Clock signals CLK are used toshift (e.g., shift in time) the third gate start pulse GSP3.

The data driver 130′ supplies a data signal to data lines D,corresponding to a data driving control signal DCS. The data signalsupplied to the data lines D is supplied to pixels PXL′ selected by ascan signal.

When the organic light emitting display device is driven at a firstdriving frequency, the data driver 130′ supplies a data signal to thedata lines D during one frame period. In this case, the data signalsupplied to the data lines D may be supplied to be synchronized withscan signals supplied to first scan lines S1 and second scan lines S2.

When the organic light emitting display device is driven at a seconddriving frequency lower than the first driving frequency, the datadriver 130′ supplies a data signal to the data lines D during a firstperiod T1 in one frame period, and supplies no data signal to the datalines D during a second period T2 except the first period T1.Additionally, the first period refers to a period in which scan signalsare supplied to the first scan lines S1 and the second scan lines S2. Inaddition, the second period refers to a period in which scan signals aresupplied to third scan lines S3.

The first scan driver 110′ supplies scan signals to the first scan linesS1, corresponding to the first gate start pulse GSP1. In an embodiment,the first scan driver 110′ may sequentially supply the scan signals tothe first scan lines S1. Here, the first scan driver 110′ supplies scansignals to the first scan lines S1 during the period in which theorganic light emitting display device is driven at the first drivingfrequency and the first period T1 when the organic light emittingdisplay device is driven at the second driving frequency.

The second scan driver 120′ supplies scan signals to the second scanlines S2, corresponding to the second gate start pulse GSP2. In anembodiment, the second scan driver 120′ may sequentially supply the scansignals to the second scan lines S2. Here, the second scan driver 120′supplies scan signals to the second scan lines S2 during the period inwhich the organic light emitting display device is driven at the firstdriving frequency and the first period T1 when the organic lightemitting display device is driven at the second driving frequency.

Additionally, when transistors coupled to the first scan lines S1 andthe second scan lines S2 are formed of the same conductivity type (e.g.,a P-type or N-type), the first scan driver 110′ and the second scandriver 120′ may be formed as one driver. This will be described infurther detail later.

The third scan driver 170 supplies scan signals to the third scan linesS3, corresponding to the third gate start pulse GSP3. In an embodiment,the third scan driver 170 may sequentially supply the scan signals tothe third scan lines S3. Here, the third scan driver 170 supplies scansignals to the third scan lines S3 during the second period T2 when theorganic light emitting display device is driven at the second drivingfrequency.

The pixel unit 100 includes pixels PXL′ located to be coupled to thedata lines D, the scan lines S1, S2, and S3, and the emission controllines E. The pixels PXL′ receives a first driving power source ELVDD, asecond driving power source ELVSS, and an initialization power sourceVint, which are supplied from the outside.

Each of the pixels PXL′ is selected when scan signals are supplied toscan lines S1, S2, and S3 coupled thereto to receive a data signal froma data line D. The pixel PXL′ receiving the data signal controls theamount of current flowing from the first driving power source ELVDD tothe second driving power source ELVSS via an organic light emittingdiode, corresponding to the data signal.

Additionally, each of the pixels PXL′ may be coupled to one or morefirst scan lines S1, one or more second scan lines S2, one or more thirdscan lines S3, and one or more emission control lines E, correspondingto circuit structures thereof. That is, in the embodiment of the presentdisclosure, signal lines S1, S2, S3, E, and D coupled to the pixel PXL′may be variously set corresponding to circuit structures of the pixelPXL′.

FIG. 24 is a circuit diagram illustrating an embodiment of the pixelshown in FIG. 23. For convenience of description, a pixel that islocated on an ith horizontal line and is coupled to an mth data line Dmis illustrated in FIG. 24. In FIG. 24, components identical to those ofFIG. 2 are designated by like reference numerals, and their detaileddescriptions may not be repeated.

Referring to FIG. 24, the pixel PXL′ according to the embodiment of thepresent disclosure includes an organic light emitting diode OLED and apixel circuit 200′ for controlling the amount of current supplied to theorganic light emitting diode OLED.

An anode electrode of the organic light emitting diode OLED is coupledto the pixel circuit 200′, and a cathode electrode of the organic lightemitting diode OLED is coupled to the second driving power source ELVSS.The organic light emitting diode OLED generates light with a luminance(e.g., a predetermined luminance) corresponding to the amount of currentsupplied from the pixel circuit 200′.

The pixel circuit 200′ controls the amount of current flowing from thefirst driving power source ELVDD to the second driving power sourceELVSS via the organic light emitting diode OLED, corresponding to a datasignal. To this end, the pixel circuit 200′ includes first to fifthtransistors M1 to M5, an eighth transistor M8, and a storage capacitorCst.

The eighth transistor M8 is coupled between a first node N1 and areference power source Vref. In addition, a gate electrode of the eighthtransistor M8 is coupled to an ith third scan line S3 i. The eighthtransistor M8 is turned on when a scan signal is supplied to the iththird scan line S3 i to supply a voltage of the reference power sourceVref to the first node N1. Here, the reference power source Vref is setto a voltage different from that of the first driving power sourceELVDD.

The pixel PXL′ shown in FIG. 24 supplies the voltage of the referencepower source Vref to the first node N1, using the eighth transistor M8,when the organic light emitting display device is driven at the seconddriving frequency. That is, a driving process of the pixel PXL′ shown inFIG. 24 is identical to that of the pixel of FIG. 2 except that thepixel PXL′ supplies the voltage of the reference power source Vref,using the eighth transistor M8. Therefore, a detailed description ofsaid elements may not be repeated. Additionally, the eighth transistorM8 may also be added to the pixels of FIGS. 8, 13, 14, 15, and 17.

FIG. 25 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 24 is driven at the first drivingfrequency.

Referring to FIG. 25, when the organic light emitting display device isdriven at the first driving frequency, scan signals are sequentiallysupplied to first scan lines S11 to S1 n and second scan lines S21 to S2n during one frame period 1F. Here, a scan signal supplied to an ithfirst scan line S1 i overlaps with that supplied to an ith second scanline S2 i.

In addition, when the organic light emitting display device is driven atthe first driving frequency, emission control signals are sequentiallysupplied to emission control lines E1 to En. Here, an emission controlsignal supplied to an ith emission control line Ei overlaps with scansignals supplied to an (i−1)th first scan line S1 i-1 and the ith firstscan line S1 i. A data signal DS is supplied to the data lines Dm to besynchronized with the scan signals.

Then, a voltage corresponding to the data signal is stored in each ofthe pixels PXL′, and accordingly, each of the pixels PXL′ generateslight with a luminance (e.g., a predetermined luminance) correspondingto the data signal DS. Additionally, third scan lines S31 to S3 nreceive a gate-off voltage from the third scan driver 170 during theperiod in which the organic light emitting display device is driven atthe first driving frequency. That is, when the organic light emittingdisplay device is driven at the first driving frequency, no scan signalis supplied to the third scan lines S31 to S3 n.

FIG. 26 is a waveform diagram illustrating an embodiment of a drivingmethod when the pixel shown in FIG. 24 is driven at the second drivingfrequency.

Referring to FIG. 26, when the organic light emitting display device isdriving at the second driving frequency, one frame period 1F is dividedinto a first period T1 and a second period T2. Here, the second periodT2 may be set as a period wider (e.g., having a longer duration) thanthe first period T1.

During the first period T1, scan signals are sequentially supplied tothe first scan lines S11 to S1 n and the second scan lines S21 to S2 n.Here, a scan signal supplied to the ith first scan line S1 i overlapswith that supplied to the ith second scan line S2 i.

In addition, during the first period T1, emission control signals aresequentially supplied to the emission control lines E1 to En. Here, anemission control signal supplied to the ith emission control line Eioverlaps with scan signals supplied to the (i−1)th first scan line S1i-1 and the ith first scan line S1 i. A data signal DS is supplied tothe data lines D to be synchronized with the scan signals. Then, duringthe first period T1, a voltage corresponding to the data signal DS isstored in each of the pixels PXL′.

During the second period T2, a plurality of scan signals are supplied toeach of the third scan lines S31 to S3 n. Here, the scan signalssupplied to each of the third scan lines S31 to S3 n may be supplied forevery set or predetermined period. In an embodiment, during the secondperiod T2, scan signals may be supplied several times to the third scanlines S31 to S3 n while being sequentially repeated.

During the second period T2, a plurality of emission control signals aresupplied to each of the emission control lines E1 to En. Here, anemission control signal supplied to an ith emission control line Ei maybe supplied to overlap with scan signals supplied to an (i−1)th thirdscan line S3 i-1 and an ith third scan line S3 i.

An operating process of the pixel PXL′ will be described. During thefirst period T1, a voltage of the data signal DS is stored in each ofthe pixels PXL′. Then, the first transistor M1 supplies, to the organiclight emitting diode OLED, a current (e.g., a predetermined current)corresponding to a difference between a voltage of the first drivingpower source ELVDD, applied to the first node, and a voltage of the datasignal DS, applied to the second node N2.

During a partial period of the second period T2, an emission controlsignal is supplied to the ith emission control line Ei. When theemission control signal is supplied to the ith emission control line Ei,and the fifth transistor M5 is turned off. Then, the pixel PXL′ is setto the non-emission state.

After that, a scan signal is supplied to the ith third scan line S3 i.When the scan signal is supplied to the ith third scan line S3 i, theeighth transistor M8 is turned on. When the eighth transistor M8 isturned on, a voltage of the reference power source Vref is supplied tothe first node N1. Then, characteristics of the first transistor M1 arechanged, and accordingly, the display quality of the organic lightemitting display device can be improved. Here, the third scan driver 170sequentially supplies scan signals to the third scan lines S31 to S3 nat least two or more times.

As shown in FIGS. 25 and 26, when transistors coupled to the first scanlines S11 to S1 n and the second scan lines S21 to S2 n are set to thesame conductivity type (e.g., a P-type), scan signals supplied from thefirst scan driver 110′ and the second scan driver 120′ are set identicalto each other. In this case, the first scan driver 110′ and the secondscan driver 120′ may be formed as one driver (e.g., one integrateddriver circuit).

Additionally, when the transistors coupled to the first scan lines S11to S1 n and the second scan lines S21 to S2 n are set to differentconductivity types (e.g., a P-type and an N-type), the first scan driver110′ and the second scan driver 120′ are set as different drivers. In anembodiment, when the third transistor M3 is set as an N-type transistoras shown in FIG. 9, the second scan driver 120′ supplies a scan signalhaving a high voltage. In this case, the first scan driver 110′ suppliesa scan signal having a low voltage, and the second scan driver 120′supplies a scan signal having a high voltage. Accordingly, the firstscan driver 110′ and the second scan driver 120′ are set as differentdrivers.

FIG. 27 is a waveform diagram illustrating gate start pulses supplied tothe first scan driver, the second scan driver, and the third scandriver, shown in FIG. 23.

Referring to FIG. 27, when the organic light emitting display device isdriven at the first driving frequency, first gate start pulses GSP1 aresupplied to the first scan driver 110′, and second gate start pulsesGSP2 are supplied to the second scan driver 120′. Here, a number offirst gate start pulses GSP1 supplied to the first scan driver 110′ isset equal to that of second gate start pulses GSP2 supplied to thesecond scan driver 120′. In addition, when the organic light emittingdisplay device is driven at the first driving frequency, no third gatestart pulse GSP3 is supplied.

When the organic light emitting display device is driven at the seconddriving frequency, the first scan driver 110′ and the second scan driver120′ supply scan signals during the first period T1, and the third scandriver 170 supplies scan signals during the second period T2. Here,because the second period T2 is set wider than the first period T1, pfirst gate start pulses GSP1 and p second gate start pulses GSP2 aresupplied to the first scan driver 110′ and the second scan driver 120′,respectively, and l (l is greater than p) third gate start pulses GSP3are supplied to the third scan driver 170.

In the organic light emitting display device and the driving methodthereof according to the present disclosure, characteristics of thedriving transistor are periodically initialized when the organic lightemitting display device is driven at a low frequency, and accordingly,the display quality of the organic light emitting display device can beimproved. In addition, each pixel is periodically set to thenon-emission state when the organic light emitting display device isdriven at the low frequency. Accordingly, the pixel can be driven underthe same condition as when the organic light emitting display device isdriven at a high frequency.

While in the above-described embodiments, various transistors aredescribed as N-type transistors and others as P-type transistors,embodiments of the present invention are not limited thereto. Forexample, embodiments of the present disclosure also include ones inwhich the N-type transistors and P-type transistors of the describedembodiments are switched, and the corresponding signal levels areinverted accordingly.

It will be understood that, although the terms “first”, “second”,“third”, etc., may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, a first element, component, region, layer or sectiondiscussed below could be termed a second element, component, region,layer or section, without departing from the spirit and scope of theinventive concept.

In addition, it will also be understood that when an element is referredto as being “between” two elements, it can be the only element betweenthe two elements, or one or more intervening elements may also bepresent.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting of the inventive concept.As used herein, the singular forms “a” and “an” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “include,”“including,” “comprises,” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof. As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items. Expressions such as “at least one of,” whenpreceding a list of elements, modify the entire list of elements and donot modify the individual elements of the list. Further, the use of“may” when describing embodiments of the inventive concept refers to“one or more embodiments of the inventive concept.” Also, the term“exemplary” is intended to refer to an example or illustration.

It will be understood that when an element or layer is referred to asbeing “on”, “connected to”, “coupled to”, or “adjacent” another elementor layer, it can be directly on, connected to, coupled to, or adjacentthe other element or layer, or one or more intervening elements orlayers may be present. When an element or layer is referred to as being“directly on,” “directly connected to”, “directly coupled to”, or“immediately adjacent” another element or layer, there are nointervening elements or layers present.

As used herein, the term “substantially,” “about,” and similar terms areused as terms of approximation and not as terms of degree, and areintended to account for the inherent variations in measured orcalculated values that would be recognized by those of ordinary skill inthe art.

As used herein, the terms “use,” “using,” and “used” may be consideredsynonymous with the terms “utilize,” “utilizing,” and “utilized,”respectively.

The display device and/or any other relevant devices or componentsaccording to embodiments of the present invention described herein maybe implemented utilizing any suitable hardware, firmware (e.g. anapplication-specific integrated circuit), software, or a suitablecombination of software, firmware, and hardware. For example, thevarious components of the display device may be formed on one integratedcircuit (IC) chip or on separate IC chips. Further, the variouscomponents of the display device may be implemented on a flexibleprinted circuit film, a tape carrier package (TCP), a printed circuitboard (PCB), or formed on a same substrate. Further, the variouscomponents of the display device may be a process or thread, running onone or more processors, in one or more computing devices, executingcomputer program instructions and interacting with other systemcomponents for performing the various functionalities described herein.The computer program instructions are stored in a memory which may beimplemented in a computing device using a standard memory device, suchas, for example, a random access memory (RAM). The computer programinstructions may also be stored in other non-transitory computerreadable media such as, for example, a CD-ROM, flash drive, or the like.Also, a person of skill in the art should recognize that thefunctionality of various computing devices may be combined or integratedinto a single computing device, or the functionality of a particularcomputing device may be distributed across one or more other computingdevices without departing from the scope of the exemplary embodiments ofthe present invention.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various suitable changes in form and details maybe made without departing from the spirit and scope of the presentdisclosure as defined by the following claims and equivalents thereof.

What is claimed is:
 1. A light emitting display device configured to bedriven at a first driving frequency or a second driving frequency thatis lower than the first driving frequency, the light emitting displaydevice comprising: pixels coupled to first scan lines, second scanlines, and data lines, each one of the pixels being coupled to one ormore of the first scan lines and to one or more of the second scanlines; a first scan driver configured to supply scan signals to thepixels through the first scan lines during a first period and a secondperiod in one frame period, when the light emitting display device isdriven at the second driving frequency, and further configured to supplyscan signals to the pixels through the first scan lines during the firstperiod and the second period in one frame period, when the lightemitting display device is driven at the first driving frequency; asecond scan driver configured to supply scan signals to the pixelsthrough the second scan lines during the first period and to not supplyscan signals to the pixels through the second scan lines during thesecond period, when the light emitting display device is driven at thesecond driving frequency, and further configured to supply scan signalsto the pixels through the second scan lines during the first period andthe second period in one frame period, when the light emitting displaydevice is driven at the first driving frequency; and a data driverconfigured to supply a data signal to the data lines during the firstperiod.
 2. The light emitting display device of claim 1, wherein, whenthe light emitting display device is driven at the first drivingfrequency, a scan signal supplied to an ith (i being a natural number)first scan line overlaps with that supplied to an ith second scan line.3. The light emitting display device of claim 1, wherein the data driveris configured to supply the data signal to be synchronized with the scansignals supplied to the first scan lines.
 4. The light emitting displaydevice of claim 1, wherein, when the light emitting display device isdriven at the second driving frequency, the first scan driver isconfigured to supply j (j being a natural number of 2 or more) scansignals to each of the first scan lines during the one frame period, andthe second scan driver is configured to supply k (k being a naturalnumber smaller than j) scan signals to each of the second scan linesduring the one frame period.
 5. The light emitting display device ofclaim 1, wherein, during the first period, a scan signal supplied to anith (i being a natural number) first scan line overlaps with thatsupplied to an ith second scan line.
 6. The light emitting displaydevice of claim 1, wherein the second period is longer than the firstperiod.
 7. The light emitting display device of claim 1, wherein thefirst scan driver is configured to supply a scan signal to each of thefirst scan lines at least twice or more during the second period.
 8. Thelight emitting display device of claim 1, wherein the data driver isconfigured to supply a voltage of a reference power source to the datalines during the second period.
 9. The light emitting display device ofclaim 8, wherein the reference power source is set to a voltage within avoltage range of data signals supplied from the data driver.
 10. Thelight emitting display device of claim 8, further comprising: emissioncontrol lines in parallel to the first scan lines, the emission controllines being coupled to the pixels; and an emission driver configured tosupply emission control signals to the emission control lines during aperiod in which the light emitting display device is driven at the firstdriving frequency, the first period, and the second period.
 11. Thelight emitting display device of claim 10, wherein an emission controlsignal supplied to an ith (i being a natural number) emission controlline overlaps with a scan signal supplied to an ith first scan lineduring at least a partial period.
 12. The light emitting display deviceof claim 10, wherein each of pixels at an ith (i being a natural number)horizontal line comprises: a light emitting diode; and a pixel circuitconfigured to control an amount of current flowing from a first drivingpower source to a second driving power source via the light emittingdiode.
 13. The light emitting display device of claim 12, wherein thereference power source is set to a voltage different from that of thefirst driving power source.
 14. The light emitting display device ofclaim 12, wherein the pixel circuit comprises: a first transistorcoupled to the first driving power source via a first node coupled to afirst electrode thereof, the first transistor being configured tocontrol the amount of current supplied to the light emitting diode, theamount of current corresponding to a voltage of a second node; a secondtransistor coupled between a data line and the first node, the secondtransistor being configured to turn on when a scan signal is supplied toan ith first scan line; a third transistor coupled between a secondelectrode of the first transistor and the second node, the thirdtransistor being configured to turn on when a scan signal is supplied toan ith second scan line; a fourth transistor coupled between the secondnode and an initialization power source, the fourth transistor beingconfigured to turn on when a scan signal is supplied to an (i−1)thsecond scan line; and a fifth transistor coupled between the first nodeand the first driving power source, the fifth transistor beingconfigured to turn off when an emission control signal is supplied to anith emission control line.
 15. The light emitting display device ofclaim 14, wherein the first transistor, the second transistor, and thefifth transistor are P-type transistors, and the third transistor andthe fourth transistor are N-type oxide semiconductor transistors. 16.The light emitting display device of claim 14, wherein the pixel circuitfurther comprises: a sixth transistor coupled between the secondelectrode of the first transistor and an anode electrode of the lightemitting diode, the sixth transistor being configured to turn off whenthe emission control signal is supplied to the ith emission controlline; and a seventh transistor coupled between the anode electrode ofthe light emitting diode and the initialization power source.
 17. Thelight emitting display device of claim 16, wherein the seventhtransistor is a P-type transistor, and is configured to turn on when thescan signal is supplied to the ith first scan line.
 18. The lightemitting display device of claim 16, wherein the seventh transistor isan N-type transistor, and is configured to turn on when the emissioncontrol signal is supplied to the ith emission control line.
 19. Thelight emitting display device of claim 16, wherein the seventhtransistor is an N-type transistor, and an ith third scan line iscoupled to a gate electrode of the seventh transistor, and wherein ascan signal supplied to the ith third scan line overlaps with theemission control signal supplied to the ith emission control line. 20.The light emitting display device of claim 12, wherein the pixel circuitcomprises: an eleventh transistor configured to control the amount ofcurrent supplied from the first driving power source coupled to a firstelectrode thereof to the light emitting diode, the amount of currentcorresponding to a voltage of an eleventh node; a twelfth transistorcoupled between a twelfth node and a data line, the twelfth transistorbeing configured to turn on when a scan signal is supplied to an ithscan line; a thirteenth transistor coupled between the twelfth node andan anode electrode of the light emitting diode, the thirteenthtransistor being configured to turn off when an emission control signalis supplied to an (i−1)th emission control line; a fourteenth transistorcoupled between the eleventh node and the first electrode of theeleventh transistor, the fourteenth transistor being configured to turnon when a scan signal is supplied to an ith second scan line; afifteenth transistor coupled between an initialization power source andthe anode electrode of the light emitting diode, the fifteenthtransistor being configured to turn on when the scan signal is suppliedto an ith first scan line; a sixteenth transistor coupled between thefirst driving power source and the first electrode of the eleventhtransistor, the sixteenth transistor being configured to turn off whenan emission control signal is supplied to an ith emission control line;and a storage capacitor coupled between the eleventh node and thetwelfth node.
 21. The light emitting display device of claim 20, whereinthe eleventh to sixteenth transistors are N-type transistors.
 22. Thelight emitting display device of claim 1, further comprising: third scanlines in parallel to the first scan lines, the third scan lines beingcoupled to the pixels; and a third scan driver configured to supply scansignals to the third scan lines during the second period when the lightemitting display device is driven at the second driving frequency. 23.The light emitting display device of claim 22, wherein the third scandriver is configured to supply no scan signal to the third scan linesduring a period in which the light emitting display device is driven atthe first driving frequency and in the first period.
 24. A lightemitting display device configured to be driven at a first drivingfrequency or a second driving frequency that is lower than the firstdriving frequency, the light emitting display device comprising: pixelscoupled to first scan lines, second scan lines, and data lines; a firstscan driver configured to supply scan signals to the first scan linesduring a first period and a second period in one frame period, when thelight emitting display device is driven at the second driving frequency;a second scan driver configured to supply scan signals to the secondscan lines during the first period, when the light emitting displaydevice is driven at the second driving frequency; a data driverconfigured to supply a data signal to the data lines during the firstperiod; third scan lines in parallel to the first scan lines, the thirdscan lines being coupled to the pixels; and a third scan driverconfigured to supply scan signals to the third scan lines during thesecond period when the light emitting display device is driven at thesecond driving frequency, wherein each of the pixels at an ith (i beinga natural number) horizontal line comprises: a light emitting diode; afirst transistor coupled to a first driving power source via a firstnode coupled to a first electrode thereof, the first transistor beingconfigured to control an amount of current supplied to the lightemitting diode, the amount of current corresponding to a voltage of asecond node; a second transistor coupled between a data line and thefirst node, the second transistor being configured to turn on when ascan signal is supplied to an ith first scan line; a third transistorcoupled between a second electrode of the first transistor and thesecond node, the third transistor being configured to turn on when ascan signal is supplied to an ith second scan line; a fourth transistorcoupled between the second node and an initialization power source, thefourth transistor being configured to turn on when a scan signal issupplied to an (i−1)th second scan line; a fifth transistor coupledbetween the first node and the first driving power source, the fifthtransistor being configured to turn off when an emission control signalis supplied to an ith emission control line; and an eighth transistorcoupled between the first node and a reference power source, the eighthtransistor being configured to turn on when a scan signal is supplied toan ith third scan line.
 25. The light emitting display device of claim24, wherein the reference power source is set to a voltage differentfrom that of the first driving power source.
 26. A light emittingdisplay device comprising: a pixel comprising: a first transistorconfigured to control an amount of current flowing from a first drivingpower source to a second driving power source via a light emittingdiode; a second transistor coupled between a data line and a firstelectrode of the first transistor, the second transistor beingconfigured to turn on when a scan signal is supplied to an ith (i beinga natural number) first scan line; and a third transistor coupledbetween a second electrode and a gate electrode of the first transistor,the third transistor being configured to turn on when a scan signal issupplied to an ith second scan line; a first scan driver configured tosupply the scan signal to the second transistor through the ith firstscan line during a first period and a second period of one frame period;a second scan driver configured to supply the scan signal to the thirdtransistor through the ith second scan line during the first period andto not supply the scan signal to the ith second scan line during thesecond period; and a data driver configured to supply a data signal tothe data line during the first period and to supply a voltage of areference power source to the data line during the second period. 27.The light emitting display device of claim 26, wherein the thirdtransistor is an N-type oxide semiconductor transistor.
 28. The lightemitting display device of claim 26, wherein the second period is longerthan the first period.
 29. Theorganic light emitting display device ofclaim 26, wherein the pixel further comprises: a fourth transistorcoupled between the gate electrode of the first transistor and aninitialization power source, the fourth transistor being configured toturn on when a scan signal is supplied to an (i−1)th second scan line;and a fifth transistor coupled between the first electrode of the firsttransistor and the first driving power source, the fifth transistorbeing configured to turn off when an emission control signal is suppliedto an ith emission control line.
 30. The light emitting display deviceof claim 29, further comprising an emission driver configured to supplythe emission control signal to the ith emission control line during thefirst period and the second period.
 31. A light emitting display devicedriven at a first driving frequency or a second driving frequency lowerthan the first driving frequency, the light emitting display devicecomprising: pixels coupled to first scan lines, second scan lines, anddata lines, each one of the pixels being coupled to one or more of thefirst scan lines and to one or more of the second scan lines; a firstscan driver configured to supply scan signals to the first scan lines; asecond scan driver configured to supply scan signals to the second scanlines; and a timing controller configured to supply a same number ofgate start pulses to the first scan driver and the second scan driverwhen the light emitting display device is driven at the first drivingfrequency, and to supply different numbers of gate start pulses to thefirst scan driver and the second scan driver when the light emittingdisplay device is driven at the second driving frequency, wherein, whenthe light emitting display device is driven at the second drivingfrequency, the timing controller is configured to: supply l (l being anatural number of 2 or more) gate start pulses to the first scan driverduring one frame period; and supply p (p being a natural number smallerthan l) gate start pulses to the second scan driver during the one frameperiod, and wherein each of the gate start pulses controls a firsttiming of a scan signal supplied from each of the first and second scandrivers.